A business process is a set of tasks performed by an enterprise to provide a service. In many instances, the performance of business processes constitutes the routine operation of an enterprise. For example, an enterprise may perform a business process in which employees of the enterprise submit reimbursement requests for travel expenses. In this example, a supervisor reviews each reimbursement request. If, in this example, the supervisor approves a reimbursement request, an accounts payable department of the enterprise writes a check to the employee. If, in this example, the supervisor disapproves a reimbursement request, an email message is sent to the employee notifying the employee that the reimbursement request was denied.
Workflows are computerized implementations of business processes. A workflow comprises a set of activities. Each activity in a workflow corresponds to a task in a business process. Each activity in a workflow is associated with computer-executable code that implements the activity. When a computer executes an instance of a workflow, the computer executes the computer-executable code implementing activities in the workflow.
When a computer executes code implementing an activity in a workflow, the code could cause the computer to perform unexpected behavior. For instance, if the code implementing an activity contains a computer virus, executing the code could cause the computer to transmit personal information. In another instance, if the code implementing an activity is poorly written, executing the code could cause the computer to crash. In many circumstances, instances of workflows are executed at a server system that provides services vital to the mission of an enterprise. Accordingly, it is unacceptable for the server system to perform unexpected behavior.